Fifty senators have endorsed a legislative measure to override the Federal Communications Commission's recent decision to deregulate the broadband industry, top Democrats said Monday.

The tally leaves supporters just one Republican vote shy of the 51 required to pass a Senate resolution of disapproval, in a legislative gambit aimed at restoring the agency's net neutrality rules.

Those rules, which banned Internet providers from blocking or slowing down websites, were swept away in a December vote led by Republican FCC Chairman Ajit Pai. Republicans had argued that the rules were too restrictive for industry, while Democrats said they provided a vital consumer protection.

The resolution aims to overturn the FCC's decision and prohibit the agency from passing similar measures in the future. It has the support of all 49 Democratic senators as well as one Republican, Sen. Susan Collins of Maine.

“With full caucus support,” said Senate Minority Leader Charles E. Schumer (D-N.Y.), one of the lawmakers spearheading the effort, “it’s clear that Democrats are committed to fighting to keep the Internet from becoming the Wild West where ISPs are free to offer premium service to only the wealthiest customers while average consumers are left with far inferior options.”

To pass the Senate, backers of the resolution must recruit one more Republican member to their ranks. The measure must survive the Republican-majority House and be signed by President Trump to take effect.

After an independent agency makes a decision — such as the FCC's net neutrality deregulation — federal lawmakers have a window of 60 legislative daysto reverse the move under the Congressional Review Act. As of last Tuesday, 40 senators had signed on to the resolution to challenge the FCC under the act. Since then, 10 more have joined the effort.

Democrats have said they plan to make net neutrality a midterm campaign issue, forcing vulnerable GOP candidates to stand with their party and adopt a position that, according to some surveys, is at odds with that of the broader public.

For years, well-heeled lawyers and lobbyists for the telecom and cable industries battled the equally formidable influence of Silicon Valley over the ground rules that would determine how the Internet functioned in the future.

The FCC voted to repeal net neutrality, or the idea that Internet service providers can't block or favor websites. See what this means for you. (Jhaan Elker,Brian Fung/The Washington Post)

That debate broke into the public consciousness in 2015, as the FCC under Chairman Tom Wheeler took the step of regulating Internet providers like legacy telephone companies. The new rules subjected companies such as AT&T and Verizon to strict bans on the blocking or slowing of Internet content. They also banned the practice of speeding up other content in exchange for extra fees, opened the door to new consumer privacy rules and even raised the prospect of future controls over the price of Internet service.

Industry groups sought to have the rules repealed — filing a lawsuit against the FCC that ultimately ended in defeat. Broadband providers said, among other things, that the FCC rules prevented them from developing innovative new business models. A three-judge panel ultimately sided with the FCC.

With the election of Trump, Republicans who opposed the regulations received another chance. Pai, who had been an outspoken critic of the rules, became the FCC's chairman, and quickly moved to dismantle the net neutrality rules.

Much as the broadband industry did in 2015, today's opponents of the FCC have vowed to open a new chapter of litigation and congressional action to reverse the vote. The first lawsuits to challenge Pai's decision could come as early as the end of this month. And a vote on the Congressional Review Act could take place this summer, depending on what Congress has on its schedule.

Opposition to the deregulation has reached new levels over the past few months.As the FCC prepared for its vote last year, the agency said it had received derogatory comments toward Pai in the issue's electronic public docket. The harassment continued offline, with Pai telling Fox News that protesters had posted signs near his home aimed at his children.

“I understand that people are passionate about policy, but the one thing in America that should remain sacred is that families, wives and kids, should remain out of it,” Pai said at the time. “And stop harassing us at our homes.”

Pai has canceled at least two public appearances since then — including a major annual address at the Consumer Electronics Show in Las Vegas — amid reports of security concerns.